Abstract: To address the research gap regarding the active tectonics and paleoseismic history of the southeastern segment of the Xiangshan-Tianjingshan Fault Zone, a comprehensive geological survey and chronological constraint were carried out on the soft-sediment deformation structures (SSDS) in the central part of the Qingshuihe Basin, which is adjacent to the Miaoshan Fold-Thrust Belt (the southeastern segment of this fault zone). The genetic mechanisms of these SSDS and their internal connections with the seismic activities of the fault zone were systematically analyzed. The results indicate that the SSDS extensively developed in the central part of the Qingshuihe Basin primarily consist of pseudofaults, slump structures, load structures, flame structures, deformed bedding, clastic dikes and tension veins. Their formation time ranges approximately from 11270 ± 1100 a B.P. to 7728 ± 36 a B.P. Most of these SSDS coexist with pseudofaults, forming specific deformation combinations with directional features. They are also stratigraphically equivalent and contemporaneous in formation age with the tension fracture veins in the loess deposits at the basin margin, exhibiting distinct earthquake-triggered characteristics. This suggests a surface response to the left-lateral strike-slip tail effect of the Xiangshan-Tianjingshan Fault Zone. The findings reveal significant seismic activities of the Miaoshan Fold-Thrust Belt during the early Holocene, with an inferred epicenter located in the central region of the Miaoshan Fold-Thrust Belt and an estimated magnitude of 6.5 ≤ M < 7.3. This research provides a novel perspective and methodology for the study of active tectonics in loess-covered areas, and offers vital empirical data and significant references for paleoseismic history reconstruction and seismic hazard assessment, thereby possessing high practical significance and reference value.